Liu Lianshan,Li Renhou£¬Gao Qi
(School of Electronics and Information Engineering,Xi'an Jiaotong University,Xi'an 710049,China)
Abstract:After studying the robustness of the tricolor against JPEG compression and additive noise,a new digital watermarking algorithm for color images was presented,in which the watermark was directly embedded into the green component of the image.The green component is blocked by size 8¡Á8 pixel,and transformed with discrete cosine transformation (DCT). The DCT blocks were selected to hide watermark information according to human visual system model.The binary watermark image was encrypted with the chaotic sequence generated by key K1£¬and hided by modifying the low frequency coefficients selected by key K2£®Experimental results show that embedding watermark in green component is more robust against lossy compression and additive noise than embedding watermark in red or blue component.When the JPEG compression ratio is equal to 37.5:1,the normal correlation value between the extracted watermark and the original watermark is 0.9809£®
Keywords:color image;chaotic sequence;digital watermark;green component